中科院蘇州納米所的研究人員利用仿生學(xué)手段,，成功揭示了古細(xì)菌的酸適應(yīng)機制，相關(guān)成果近日發(fā)表于《科學(xué)報告》,。
古細(xì)菌是一類不含細(xì)胞核和膜包圍細(xì)胞器的單細(xì)胞生物,，多生存于高溫、高鹽,、高壓或極端pH值等極端環(huán)境中,。古細(xì)菌對極端環(huán)境的適應(yīng)機制一直是微生物領(lǐng)域的研究熱點之一。科學(xué)家曾經(jīng)發(fā)現(xiàn),，在組成嗜酸古細(xì)菌細(xì)胞膜的脂質(zhì)分子中,，糖脂的比例遠(yuǎn)遠(yuǎn)高于其他種類生物的細(xì)胞膜，但由于缺乏合適的工具和手段,，糖脂在質(zhì)子防御中的作用并未得到足夠充分的研究,。
蘇州納米所馬宏偉課題組創(chuàng)造性地引入仿生學(xué)手段，將內(nèi)部富含羥基的表面高分子膜——聚甲基丙烯酸寡聚乙二醇酯作為仿生高分子層,，模擬嗜酸古細(xì)菌表面糖脂所形成的富含羥基的糖被,，從而定量研究羥基基團在嗜酸古細(xì)菌酸耐受機制中的作用。研究人員通過使用納克級靈敏度的實時監(jiān)測設(shè)備——石英晶體微天平,，證實了該仿生高分子層具有顯著的質(zhì)子屏蔽作用,，可在pH值為1.0的酸性液體環(huán)境中長期維持pH值≥5.0的局部微環(huán)境。通過共聚和嵌段聚合,，研究人員成功對質(zhì)子屏蔽能力進行了系統(tǒng)的研究和細(xì)致的調(diào)制,，并初步驗證了其在三維空間中的作用效果。
研究人員發(fā)現(xiàn),，當(dāng)相同濃度的單體分子溶解于溶液中時,，游離的羥基并不表現(xiàn)出質(zhì)子屏蔽特性，說明該性能依賴于高分子主鏈對羥基的固定和富集,。在自然界中,，嗜酸古細(xì)菌則巧妙地利用了組成細(xì)胞膜的脂質(zhì)分子骨架來“兼任”這一角色,。脂質(zhì)骨架致密排列,，可行使固定和富集羥基的功能。
該仿生研究定量揭示了嗜酸古細(xì)菌的一項低pH適應(yīng)機理,，明確證實了羥基的質(zhì)子屏蔽作用,，其成果可應(yīng)用于防酸材料的開發(fā)。而研究中所構(gòu)建的仿生體系可繼續(xù)應(yīng)用于其他防酸分子和基團的評價與篩選,，有望發(fā)展成為一套標(biāo)準(zhǔn)化的質(zhì)子屏蔽研究系統(tǒng),。(生物谷Bioon.com)
doi:10.1038/srep00977
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Force and scleraxis synergistically promote the commitment of human ES cells derived MSCs to tenocytes
Xiao Chen, Zi Yin, Jia-lin Chen, Wei-liang Shen, Huan-huan Liu, Qiao-mei Tang, Zhi Fang,Lin-rong Lu, Junfeng Ji & Hong-wei Ouyang
As tendon stem/progenitor cells were reported to be rare in tendon tissues, tendons as vulnerable targets of sports injury possess poor self-repair capability. Human ESCs (hESCs) represent a promising approach to tendon regeneration. But their teno-lineage differentiation strategy has yet to be defined. Here, we report that force combined with the tendon-specific transcription factor scleraxis synergistically promoted commitment of hESCs to tenocyte for functional tissue regeneration. Force and scleraxis can independently induce tendon differentiation. However, force alone concomitantly activated osteogenesis, while scleraxis alone was not sufficient to commit, but augment tendon differentiation. Scleraxis synergistically augmented the efficacy of force on teno-lineage differentiation and inhibited the osteo-lineage differentiation by antagonized BMP signaling cascade. The findings not only demonstrated a novel strategy of directing hESC differentiation to tenocyte for functional tendon regeneration, but also offered insights into understanding the network of force, scleraxis and bmp2 controlling tendon-lineage differentiation.
